The Ertsberg Intrusion (EI) is located approximately 1.5 km southeast of the Grasberg super-porphyry Cu-Au deposit (GIC), in the Gunung Bijih (Ertsberg) Mining District, West Papua, Indonesia. Intrusion- and carbonate-hosted mineralization is associated with the 3.28-2.97±0.54 Ma multi-phase intrusive complex. The orientation of the intrusion-hosted mineralized zone is parallel to the direction of porphyry dike emplacement in the intrusive complex and to regional structures. Potassic, phyllic, propylitic and endoskarn alteration types are recognized in the EI, distributed over 7 vein types. Three vein stages initiate pre-porphyry dike emplacement, and mineralization occurs pre- and post-dike emplacement. Cu-Au mineralization is associated with pre-dike biotite-bornite-anhydrite veinlets (Stage III), and post-dike quartz-anhydrite-bornite+chalcopyrite//green sericite veins (Stage V), and quartz-anhydrite-chalcopyrite-pyrite//white sericite veins (Stage VI). Sulfides associated with each alteration type in the EI have d³⁴S values that range between -3.0 to 3.6‰. Sulfate d³⁴S between alteration types are variable: potassic (9.6- 11.1‰) and hydrolytic (10.2-16.6 ‰). The bulk isotopic sulfur (d³⁴S(SS)) composition for fluid in equilibrium Stage III veins is 7.5‰, which is higher than would expected for an oxidized calc-alkaline fluid, thus I invoke the addition of heavy sulfur from the sedimentary anhydrite nodules in adjacent carbonate host rocks. There is an overall decrease in bulk isotopic sulfur (d³⁴S(SS)) composition for hydrothermal fluid throughout the span of hydrothermal activity. A degassing mafic magma chamber at depth, and/or the leaching of previously deposited sulfides are likely responsible for this decrease. Sulfide-sulfate equilibrium temperatures for potassic alteration in the EI average 574°C, approximately 125°C cooler than sulfide-sulfate equilibrium temperatures in the GIC. Calculated oxygen isotopic compositions for water in equilibrium with anhydrite from early potassic veins in both the Ertsberg Stockwork Zone and GIC suggest this component was derived from a non-magmatic source; the sedimentary anhydrite nodules are a probable source. The calculated oxygen and hydrogen isotopic compositions for water in equilibrium sericite from intermediate veins in the ESZ and GIC show the fluid was derived from a magmatic water and/or magmatic vapor; however, the water responsible for late hydrolytic alteration in both intrusive centers provides evidence for mixing of magmatic water (vapor) with meteoric water. Mass balance calculations using the EI volume estimate, and the known mineralization associated with the EI show that the EI has an insufficient volume of H₂O to account for the known volume of hydrothermal alteration and mineralization. Coupled with sulfur, oxygen and hydrogen isotope data, and Re-Os isotope source data, this suggests additional input of hydrothermal fluids from deeper magmatic and sedimentary sources, with moderate addition of meteoric water into the hydrothermal system during Stage VI vein formation.

Fossil plants in the Upper Triassic Chinle Formation are preserved in fluvial channel, overbank, and lacustrine deposits. Plant-bearing units in these deposits are classified into seven types based on these depositional environments or subenvironments. Taphonomic characteristics of these assemblages, and of individual plant fossils within them, indicate that most plant fossils have either not been transported far from their growth sites or are preserved in situ. One particular deposit in the central part of Petrified Forest National Park preserves fossil plants in three associations: (1) allochthonous logs in basal lags in a channel-fill/lateral accretion deposits; (2) autochthonous horsetail trunks and parautochthonous horsetail leaves in a crevasse-splay deposits; and (3) parautochthonous and autochthonous cycadaceous, fern and other types of leaves, and erect and prostrate trunks in a paludal/distal splay deposits. Exposures of contemporaneous high-sinuosity channel and overbank deposits in this area enabled the reconstruction of the local paleogeography, paleohydrology, and paleoecology at a high resolution. Fossil plant assemblages of the Upper Triassic Chinle Formation are concentrated in the lower members of the formation. The lower part of the Chinle Formation was deposited in an incised valley system. Depositional, hydrological, and near-surface geochemical conditions in the incised valley system were conducive to preservation of terrestrial organic material, even though regional conditions were characterized by seasonal/monsoonal precipitation and groundwater conditions. Fossil plant assemblages preserved in these types of fully terrestrial incised valley-fills are taphonomically biased towards riparian wetland environments.

Marine upwelling occurs when surface currents diverge or are deflected. Deeper water, often nutrient-rich, rises and generates a cascade of biological effects including elevated productivity and a unique assemblage of organisms. Macrofaunal characteristics of upwelling provide key evidence for oxygen-minimum zones, upwelling of cool water, and high productivity and are potentially useful indicators of ancient upwelling. The Upper Triassic Luning Formation in Nevada contains abundant, large ichthyosaurs and was deposited in a back-arc basin that could have experienced upwelling conditions. Luning Formation rocks at West Union Canyon were analyzed for sedimentological, geochemical, and paleontological upwelling indicators. Abundant suspension feeders, lack of corals and calcareous algae, modest total organic carbon and minor element concentrations in deeper marine facies, abundant cosmopolitan molluscs but no taxa restricted to low latitudes, and abundant fecal pellets and clotted fabrics in most facies suggest that upwelling could have influenced Luning deposition. Moderate-scale upwelling likely contributed to eutrophic conditions and ichthyosaur abundance at West Union Canyon. Marine reptiles might have had ties to upwelling areas to provide food, as do modern whales. A relational database containing 817 locality records and 1365 taxon-localities was assembled for ichthyosaurs, plesiosaurs, and mosasaurs. Marine reptile localities were compared with model-predicted upwelling and with upwelling-related lithologies (organic-rich rock, biogenic silica, phosphorite, and glauconite). Marine reptile occurrences intersected predicted upwelling more often than expected by chance for the Upper Cretaceous, Callovian, and Norian stages, and for all of the data together (P = 0.05). For age-restricted data, occurrences of Mosasauridae, Pliosauridae, and Plesiosauria intersected upwelling more often than expected by chance (P = 0.05). Average shortest distances between reptile fossil and upwelling lithology occurrences were smallest (one grid cell adjacent or smaller) for the Pliensbachian and four of five Cretaceous stages. Analytical biases and other aspects of reptile ecology may have affected the results, but overall, upwelling could have influenced marine reptile distribution, particularly for the Upper Cretaceous. Multiple radiations into the high-productivity, top-predator niche over the Mesozoic are suggested by the dominance of different taxa in grid cells containing upwelling lithologies: ichthyosaurs (early Mesozoic), plesiosaurs (middle Mesozoic), and finally mosasaurs (late Mesozoic).

Pb isotopic compositions of twelve Late Cretaceous-Early Tertiary (LC-ET) igneous complexes in Arizona suggest that there are no isotopic distinctions between productive (those that host a porphyry copper deposit) and barren complexes. Pb isotopic compositions of the LC-ET igneous rocks are similar to those of the Proterozoic basement rocks in which they are located and indicate a regional coherence and inheritance of Pb isotopic compositions. Within the LC-ET igneous complexes, there is commonly a decreasing trend in 206Pb/204Pb from the oldest to youngest pluton. In Arizona, the sulfide mineralization in porphyry copper deposits is generally spatially and temporally associated with the youngest plutons. Pb isotopic compositions of the sulfide mineralization suggest that much of the mineralization was deposited from fluids with an isotopic composition similar to the plutons lowest in 206Pb/204Pb, (the younger plutons). The low 206Pb/204Pb values of the younger plutons and sulfide mineralization suggest derivation from a lower crustal source. Not all the sulfide mineralization has the same Pb isotopic composition. Some distal mineralization, later stage mineralization, and mineralization hosted in Precambrian rocks have Pb isotopic compositions higher in 206Pb/204Pb. The higher 206Pb/204Pb suggests that these mineralizing fluids interacted with upper crustal rocks. Ag/Au ratios of LC-ET igneous complexes and Middle to Late Tertiary metallic mineral districts in Arizona geographically correspond to Pb isotopic provinces. Pb isotopic compositions and model Th/U for sulfide mineralization from 50 of the metallic mineral districts mimic regional Pb isotopic trends defined by Early Proterozoic whole rocks. Crustal provinces with Th/U higher or lower than the crustal average (Th/U≅4) have a higher potential for Au-enriched ore deposits. Crustal provinces with Th/U≅4 have a higher potential for Ag-enriched ore deposits. The Pb isotopic data presented here are consistent with the crustal inheritance of metal ratios. Thus, the crustal inheritance hypothesis can be used as a viable exploration technique at the crustal-province scale. Mass spectrometers that also have the capability of rapid elemental analyses (ICPMS) and aeroradiometric data are useful tools for this exploration method.

The use of intramural space is examined in and between structures from the Hohokam site of Snaketown, Arizona. The approach advocated in this volume results from a disenchantment with the efficacy of pre-established functional categories for characterizing structure use and accounting for the variability present. In an effort to transcend the vague concept of house function categories of use-areas are defined which represent widespread regularities in the way intramural space is used and arranged. The latter are identified on the basis of spatial patterns of use that are visible cross-culturally in ethnographies and ethnoarchaeological reports and through the examination of artifact and feature arrangments in the archaeological sample from Snaketown. House types, defined on the basis of differing combinations of use-areas, are examined in the context of spatial aggregates of houses, courtyard groups. Their distributions serve as a basis for deriving inferences regarding the nature, localization, and size of cooperating economic groups at the site. Replication of use-area categories and house types within and between courtyard groups, indicates that cooperating economic groups existed at various levels at Snaketown, both above and below the level of the courtyard group.

Over the past two decades, several competing dynamic models have emerged to explain the tectonic evolution of the Himalayan thrust belt. Basic aspects of the geology of the range remain relatively poorly known, however, limiting the accuracy of dynamic and kinematic models. For example, the location of a mega-thrust now exposed in the interior of the range, the Main Central thrust (MCT), is only approximately known across much of the Himalaya. Both because the MCT accommodated at least 150 kilometers of slip during the mid-late Tertiary and because it carries in its hanging wall the highest-grade metamorphic rocks exposed in the range, the MCT is a prominent feature in all models that seek to explain the tectonic evolution of the Himalaya. Whole-rock Nd isotopes and detrital zircon U-Pb ages allow the discrimination of hanging wall and footwall rocks of the MCT. Application of these techniques in the Annapurna Range of central Nepal unambiguously locates the MCT. Microstructural analyses confirm the presence of a thrust-sense ductile shear zone superimposed on this isotopic boundary.With improved locations of the MCT and other faults, it is now possible to understand thermobarometric and kinematic data in more correct structural context. Thermobarometric estimates demonstrate that rocks exposed in fault-bounded blocks in the Modi Khola transect experienced approximately constant peak conditions, and that peak conditions change dramatically across large faults. Pressure-temperature estimates combined with constraints on the extent of metasomatism indicate the presence of a large normal fault one kilometer structurally above the MCT. Preliminary Th-Pb dating of monazite suggests that this normal fault may have been active during slip on the MCT. The presence of such a proximal normal fault slipping synchronously with the MCT challenges some current representations of dynamic models for the evolution of the thrust belt. In situ Th-Pb ages of monazite inclusions in garnet, chemical and age zoning in the inclusions, and textural relationships between monazite, garnet, and nearby minerals demonstrate that interpretation of the tectonic significance of Tertiary Th-Pb ages from matrix monazite is simpler than interpretation of ages from inclusions in garnet.

In the Basin and Range province of southwestern North America, Oligocene and Miocene normal faults are superimposed upon the Late Cretaceous-early Tertiary magmatic arc. This study examines tilted fault blocks containing dismembered pieces of porphyry systems, including pieces below and peripheral to ore bodies, that are exposed at the modern surface. Features in the magmatic-hydrothermal porphyry systems are used to place constraints on the style of extension in Arizona, and reconstructions of extension are used to examine the deep and peripheral portions of porphyry systems to provide a more complete understanding of porphyry systems as a whole. The Eagle Pass, Tea Cup, and Sheep Mountain porphyry systems of Arizona are examined in this study. In all the study areas, previous interpretations of the style of extension involved strongly listric normal faults. However, similar amounts of tilting observed in hanging wall and footwall rocks, as well as structure contour maps of fault planes, require that down dip curvature on faults was minimal (<1°/km. Instead, extension is shown here to have occurred as sets of nearly planar, "domino-style" normal faults were superimposed upon one another, including in the Pinaleño metamorphic core complex. Reconstructions of Tertiary extension reveal that sodic (-calcic) alteration is occurs 2-4 km peripheral to, and greisen alteration is found structurally below and overlapping with, potassic alteration. In addition, a preliminary reconstruction of extension across the Laramide magmatic arc reveals that the geometry, as revealed by known porphyry systems, is of similar scale to that of other magmatic arcs. These results help further the debate surrounding competing models of continental extension, and combine with previous work to provide a more complete understanding of the geometries of Arizona porphyry systems at the district and arc scale.

Stratigraphic records in Middle Park in north-central Colorado provide evidence for the late Quaternary geomorphic and environmental history of a non-glaciated Southern Rocky Mountain basin. Episodes of geomorphic instability apparent in the stratigraphic record coincide with changes in paleoenvironmental records from above 2750 m in north-central Colorado, suggesting that the western Middle Park landscape was sensitive to environmental changes affecting the region over the last ~14,000 years. Tributaries were incised prior to 14.0 ka, but deposits older than 12.0 ka are rare. Upland erosion and incision followed by rapid aggradation in alluvial settings between 12.0 and 11.0 ka coincide with evidence for regional temperatures at or above present, and is interpreted to signal the onset of Holocene summer-wet precipitation. A widespread soil-stratigraphic marker represents a long period of landscape stability between <11.0 and 6.0 ka in upland and alluvial settings. Pedologic evidence from upland settings indicates the expansion of grass and forest cover to lower elevations that today are characterized by sagebrush steppe, probably during a period of increased summer precipitation relative to present. During the late Holocene, episodes of aggradation in alluvial valleys at 6.0-1.0 ka and 0.6-0.2 ka and soil formation in uplands at 5.0-3.5 ka and 2.5-1.0 ka overlap with evidence for cooling at higher elevations. Incision of valley floors documented at 1.0-0.6 ka and during the last few centuries and episodes of erosion in uplands at 3.5-2.5 ka, after 1.0 ka, and within the last few centuries, are roughly synchronous with evidence for warming. Upland and alluvial stratigraphic records are interpreted to indicate that during cool intervals summer precipitation was diminished, resulting in relative hillslope stability and gradual valley bottom aggradation, while pulses in summer precipitation accompanying warmer episodes caused basin-wide geomorphic instability. The recent increasing frequency of geomorphic instability appears to correspond with an increase in sagebrush steppe at the expense of forest and grass cover, interpreted to represent progressive drying during the late Holocene. It stands to reason that future warming, if accompanied by similar patterns in precipitation, will result in continued erosion on a landscape already at a threshold of geomorphic instability.

Sedimentary deposits in the Salton Trough of California record the infilling of the northern part of the Gulf of California. The final phase of deposition began about 4.0 Ma with development of the delta plain of the Colorado River and ended about 0.9/0.7 Ma after a period during which deposition was dominated by bedload streams. During the final phase of deposition, a diverse assemblage of mammals characteristic of the Blancan and Irvingtonian Mammal Ages inhabited the area. The Blancan-Irvingtonian boundary is placed in the Fish Creek-Vallecito Creek section at the lowest stratigraphic occurrence of Hammuthus at about 1.77 Ma. The Fish Creek-Vallecito Creek section contains superposed Blancan and Irvingtonian faunas separated by a newly recognized Blancan-Irvingtonian boundary in continuously deposited sediments correlated with the magnetic polarity time scale. It is proposed that the Fish Creek-Vallecito Creek section be recognized as the standard section in which to define the Blancan-Irvingtonian boundary. Taphonomic analysis indicates that skeletal elements accumulated in five major depositional environments: tidal flat, lacustrine, channel, channel "fill", and floodplain. Only the fluvial environments produced significant skeletal abundances and taxonomic diversity. Taphonomic analysis indicates that pre-transport taphonomic processes were more important than fluvial transport in modifying thanatacoenoses. Taphonomic analysis also suggests that taxonomic diversity and relative abundances of large and small mammals are reliably preserved so that assemblages can be used in realistic, but general, analyses of paleoecology and paleocommunity structure. Actualistic and cenogram methods were used to study the Fish Creek-Vallecito Creek paleocommunity. Both methods suggest a savannah-community. The cenogram analysis shows the structure of the paleocommunity based on body size distribution. The data are grouped into assemblages based on the following criteria: change in fluvial environment, change in taxonomic composition, and change in paleoclimate. Stable, discrete small- and large-sized components with homogeneous body-size distributions are separated by an unstable medium-sized component. Results are consistent regardless of how the data are grouped, suggesting confidence in the results, stability in the paleocommunity despite environmental change, and a reality to the existence of the paleocommunity.

The United Verde orebody, a Proterozoic volcanogenic massive sulfide deposit, is hosted by the Cleopatra Formation. The Cleopatra Formation is subdivided into two distinct members, the Upper and Lower, on the basis of alteration facies, whole rock geochemistry and the chemistry of alteration minerals. The Lower member was deposited prior to ore deposition and consists of five major alteration facies. Facies Bl, the most distant from the orebody represents the recharge area for the ore-forming fluid. Facies B2 surrounds the major discharge area or the chlorite pipe. These three facies contain chlorite and quartz as alteration minerals in variable amounts. Two facies, 81 and S2, contain quartz and sericite as alteration minerals. Mass balance calculations show progressive removal of Na and Ca, and addition of MgO and FeO* from the area of recharge (facies Bl) to facies B2 to the chlorite pipe. Whole rock δ¹⁸O values are high relative to least altered Cleopatra Formation in the recharge area and low in the discharge zone. Mineralogy and geochemistry of samples from the Upper member indicate that it was deposited following ore deposition and interacted with fluids rich in silica and iron. The hydrothermal fluid, which is interpreted to have been seawater, evolved to a high temperature slightly acidic, reduced fluid during water-rock interaction(log a₀₂ = -33 to -41; log a(H2S) = -2.6 to -5.0). The fluid δ¹⁸O and δ¹³C₀₂ values increased. Calculated δ¹³C₀₂ and δ¹⁸O fluid values, and sphalerite and chlorite chemistry imply that mixing of the hydrothermal fluid with seawater occurred in the orebody. the upper The levels of the chlorite pipe and in limited range in δ³⁴S values of sulfides is consistent with the derivation of the oreforming fluids from the reduced basal layer of a stratified basin. The study area represents only a small part of the United Verde circulation cell. Increased δ¹⁸O values of the fluid, and the need for a source of Mg, Fe and other metals suggest that the fluids may have circulated into the Shea Basalt.

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